Primary intestinal follicular lymphoma presenting as multiple lymphomatous polyposis.

Multiple lymphomatous polyposis (MLP) is a rare condition, described in the literature as a presentation of extranodal mantle cell lymphoma. We report a rare case of follicular lymphoma presenting as MLP in a young woman with a short history of haematochezia who underwent colonoscopy. Immunohistochemistry on colonic biopsies confirmed follicular lymphoma. Microscopic examination found an extensive and dense lymphoid infiltrate, which demonstrated a follicular growth pattern. The neoplastic cells were positive with BCL2, BCL6, CD10 and CD20, and were negative with CD3, CD5, Cyclin D1 and SOX11. CT staging showed disseminated lymphadenopathy and the patient was commenced on chemotherapy. Endoscopic evaluation and histopathological analysis are vital for the accurate diagnosis of MLP. Our case demonstrates that follicular lymphoma should be considered as a differential, as not all cases of diffuse colonic MLP are related to mantle cell lymphoma. This distinction must be made to provide the best clinical management for the patient. © BMJ Publishing Group Limited 2020. No commercial re-use. See rights and permissions. Published by BMJ.